It was announced at the company's Worldwide Developers Conference on June 7, 2021, as the successor to iOS 14 and released to the public on September 20, 2021.

Based on the selected state, users can set the type of notification they want to receive and from which application.

[9] Devices with an A12 chip or later support Live Text, which uses optical character recognition to recognize text in images, allowing copy-and-paste, look-up, and translation in Photos, Screenshot, Quick Look, Safari, and Live Preview with Camera.

[12] The various Home screens can be reordered, deleted, hidden, or limited using Focus mode.

[12] The global search function has been enhanced and it is also available on the lock screen by pulling the page down.

[16] The system default player, used for videos and by many apps, supports changing playback speed.

The users can tap this option, select a specific in-app purchase and identify the problem that led to the refund request.

[28][better source needed] iOS 15 adds several new features to FaceTime, including:[29] Memoji in iOS 15 have more customization options, including new clothing, two different eye colors, new glasses, new stickers, multicolored headwear, and new accessibility options.

[36][37] In the Photos app, the user can now look up places that are inside images; however, this feature only works on the Apple A12 chip or later.

[38][39][40][41] Improved panoramic shooting mode on iPhone 12 and above: less geometric distortion in panoramic shots with elongated fields of view, noise and banding reduction that are formed in the image due to changes in brightness and contrast when moving the camera from side to side, a less blurry and clearer image even when capturing moving subjects within the panorama.

The app also has a next-time precipitation notifications feature which allows the user to get a notification whenever rain or snow is going to start or stop within the next hour for the user's current location and each saved location, independently.

[46] Siri can now work offline on iPhones with an A12 Bionic chip or later, responding faster to common requests supported locally without need for Internet connection.

[50][better source needed][51][52][53] A new monitored parameter called "Walking Steadiness" has been added, which determines the risk of falling using gyroscopic sensors that measure balance, stability, and coordination.

This feature was called "Record App Activity" until iOS 15.2, when its functionality was extended.

[59] Safari's anti-tracking now prevents known trackers from reading the user real IP address.

In this way it is possible to privately download this external content without being tracked by spammers or commercial companies that have inserted them without the user's knowledge.

Private Relay masks the user's IP address in Safari, preserving the region without revealing the actual location.

The built-in authenticator allows iOS devices to be used to generate verification codes for additional sign-in security of accounts.

[66] iOS 15 introduced kalloc_type in order to advance memory safety in the XNU kernel.